16.10 - Sessions and Instances - Parallel Transporter

Teradata Parallel Transporter Reference

Parallel Transporter
Release Number
July 2017
Content Type
Programming Reference
Publication ID
English (United States)

A minimum and a maximum number of sessions (the session limits) can be specified for the Load operator. Both can also be specified for the Export and Update operators.

Consider the following usage notes which apply to all three types of operators.

  • The maximum sessions connected can never exceed the number of available AMPs in the system, even if a larger number is specified.
  • The default is one session per available AMP.
  • For the MinSessions attribute, the minimum specification is one.
  • The MaxSessions attribute can be set to a number smaller than the number of AMPs on the database server if fewer sessions are suitable for the job.
  • Network protocol software might also impose limits on network-attached systems.
  • Platform limits for maximum sessions per application differ:
    • On mainframe-attached z/OS client system, use the TDP SET MAXSESSIONS command to specify a platform limit.
    • On network-attached client systems for UNIX, Linux, and Windows systems, this value is defined in the CLI file, clispb.dat, under the max_num_sess variable.
    • On mainframe-attached z/OS client systems, this value is defined in the HSHSPB parameter under the IBCSMAX setting.

      The max_num_sess value in the clispb.dat file (or HSHSPB) specifies the total number of sessions allowed to be connected by a single application at one time. For the Export, Load, and Update operators, two types of sessions are counted toward the max_num_sess value: SQL sessions, and specialized data loading sessions that have a restriction of one per AMP.

      The max_num_sess pertains to all sessions connected, both SQL and data loading.